System of position finding by electromagnetic waves



Jan. 2, v1951 A. DE sAlNT-l-:XUPERY 2,536,728

SYSTEM 0F POSITION FINDING BY ELECTROMAGNETIC WAVES 5 Sheets-Sheet lFiled June 4, 1941 Jim 2 1951 A. DE sAlNT-l-:XUPERY 2,536,728

SYSTEM OF POSITION FINDING BY ELECTROMAGNETIC WAVES Filed June 4, 1941 5Sheets-Sheet 2 L @if We@ M75/M J l S.

Jan- 2, 1951 A. DE SAINT-EXUPERY 2,536,728

SYSTEM oF PosITIoN FINDING BY ELEcTRoNAGNEIIc wAvEs Filed June 4, 1941 5Sheets-Sheet 5 /LLATOR P/ME Patented Jan. 2, 1951 ISYSTEM OF POSITIONFINDING BY ELECTROMAGNETIC WAVES Antoine de Saint-Exupry, New York, N.Y.; vested in the Attorney General of the United States Application June4, 1941, Serial No. 396,530 In France February 19, 1940 Section 1,Public Law 690, August 8, 1946 Patent expires February 19,V 1960 12Claims.

The present invention relates to new and improved. methods 'of andapparatus for locating the site of an unknown position relative to oneor more lixed points, the locations of which are known.

Theinvention is based on the retransmission, from `the fixed base pointor points, of suitable signals transmitted from the unknown position,andcbserving at the latter position the registration of theretransmitted signals as upon a suitably energized cathode ray tube oroscillograph.

One of the objects of the present invention `is to provide new andimproved methods of and apparatus for determining the distance betweenan unknown position and one or more lixed base points, the locations ofwhich are known.

`Another object of the invention is to provide new and improved methodsof and apparatus for determining the bearing of an unknown positionrelative to one or more fixed points, the locations of which are known.

`A further object of the present invention is to provide a new andimproved method of navigationwhen in communication with either one ortwo xed base points.

Another object of the invention is to provide new and improved methodsof and apparatus for navigating along a given route, for approaching alanding field, and for `determining the location of a point in spacerelative to'two or more iixed base points which `are spaced apart atknown locations.`

Other objects and advantages of the invention will" become apparent fromthe ensuing description, inthe course of which reference is had to theaccompanying drawings, in which:

Fig. 1 is a diagrammatic representation of the apparatus located on avessel, for instance, an aerial or naval vessel, or the like, whoseunknown position is to be ascertained.

Fig. 2 is a front elevational view of the. cathode ray tube forming partof the apparatus illustrated in Fig.A l and showing the cathode raytrace formed on the screen thereof when the apparatus is used inaccordance with one of the methods of the present invention;

Figs. 3 and 4 are views similar to Figs. 1 and 2, respectively. anotherembodiment of the apparatus and a trace obtainable by its use;

. Fig. 5 is another view similar to Fig. l of a further embodiment ofthe apparatus located at an unknown position; and

Fig. 6 is a diagrammatic representation of an embodiment involvingapparatus at the unknown position and at a plurality of xed base points.rlnFigure 1 is illustrated diagrammatically a form of apparatusconstituting station A, carried on the airplane, boat, or the like,whose position relative to certain fixed stations is to be ascertainedor determined. VIn the following description it is assumed that theapparatus at station A is located on an airplane.

The apparatus consists, in the main, of a cathode ray tube I0, a radiotransmitter II, a radio receiver I2, and a plurality of oscillators andphase shifters I3 to I6, inclusive. The antenna 63 of the `receiver maybe either fixed or rotated for purposes described hereinafter. While aplurality of oscillators and phase Shifters are shown, only one of theseis utilized at `any one time, and,` as a matter of fact, most of themethods of this invention may be practiced with apparatus including butone.

The cathode ray tube is provided with the usual pairs of rectangulardeector plates Il and I8. These are supplied with two sinusoidalcurrents of equal intensity and frequency but `displaced in phase,thereby to cause the cathode ray beam to describe a cone, the trace ofwhich is a circle on the uorescent screen of the tube. Inasmuch as therotation Iis not mechanical in nature, it may be as rapid as desired.For instance, the rotational velocity of the radius vector of the circlemay be 1,000 revolutions per second, or as low as 41% cycles per secondand as high as 10,000 cycles per second.- The currents are selectivelysupplied to the deector plates from the phase Shifters and oscillatorsby means of a selector switch comprising the two simultaneously movableblades I9. One of these blades is connected by a conductor 20 to one oftheY deector plates II, the other plate Il being grounded, and the otherof the switch blade is connected by a conductor 2| to one of deflectorplates I8, the other plate I8 being grounded. In the indicated positionof the selector switch shown in Figure 1, the deector plates areconnected to oscillator I5, supplying a current having a frequency of1,000 cycles per second. When the switch blades I9 are in theiruppermost or first position, the deector plates are connect-ed tooscillator and phase shifter I3, supplying a current having a frequencyof 41% cycles per second. In the second position of the switch, thedeector plates are connected to oscillator and phase shifter I4,supplying a current having a frequency of 416% cycles per second; and inthe fourth or lowermost position of the switch, the plates are connectedto oscillator and phase shifter I6 supplying a current having afrequency of 10,000 cycles per second.

- The oscillators and phase Shifters are of iden,

Oscillator and phase shifter I3 isthe only onel illustrated, andcomprises a tube 4'22 and the mutually coupled coils 23, 2li and 25.Coil 23 is shunted by a condenser 2t, these two elementsr being chosento give the desired frequency, in. a'ccordance with well-known practice.Coil 25, which may be termed an output coil, is shunted by a resistor 21and a condenser '28 connected in series and having their junction pointgrounded by conductor 29, thereby to provide the delector plates I? andI8 with currents Athat are displaced 90 from each other.

The cathode ray tube includes the usual anode 3|, indirectly heatedcathode 32, screen .33, alz1d grid 34. These are supplied with properpotentials from a suitable source (not shown) 'through conductors 435and a potentiometer indicated generallyby reference character 36. Inorde-r to provide for observing `th'e appearance of alphenom'enon havingvthe same periodas the rotation of the radi-us vector but orundetermined phase, various methods may be used'. For instance, it ispossible to cause the current feeding the cathode Vray tube deflectorsto be modulated lby the phenomenon. -It is possible also to feed asystemA of -two concentric rings with a current which'is a function oi"the intensity of the phenomenon, the lconcentric deflecting rings beingpositioned above the deectors and so `located with respect theretolthatthe cone described by theradius Vector nmay `pass and` clear" therings; The current passing through the rings will effect anveirclusiifely'radial Variation ofthepoint of im pact of the cathoderays on the screen without an'yvariatlion ofthe polar angle at 'thatmoment (acathode tube of this kind having, inf-particular,be'nfsuggest'ed-by 4Von Ardenne) 1Itfis-ob`vious that, if'thephenomenonis la "c `metant phasepulse, -it will make VVitself manifest on theuo'r'e'scent screen by the` appearance "o'fY a stationary tooth.

The'cathodera'y tube-l `of the embodimentlillustra-t'ed in Fig. l is`provided with twoconcentric rings 37 and E33. -The concentric ring 38Yis supplied with periodic pulses from thetrans'mitte`r if! through aconductor 39.Y Itis alsofsu'p'plied with pulsesretransmitted lfrom oneof thexed base point stations,- to which further reference will be hadshortly, :by `means Aof 4vthe receiver ll2v, therectied output of whichis connected tothe ring-by conductor t0. A synchronizing s'ignalvissuppliediromthe-oscillator and-phase shifter to the 'transmitter througha conductor 4 I.

Figure 2 shows d-iagrammatica1ly how the-circular trace of the cathoderay becomes-modiiied to producestationa'ry teeth. A rst tooth,indicatedfbyreierence character 42, isproducedrwhen the 'transmittersends out a pulse, this tooth resulting-from the supply of current tothe -deiiie'cting lrings through conductor 3.9i. A second tooth,indicated. by reference character 43, is produced when the retransmittedpulse ispicked up byre'- ceiver i2 and awcurrent proportionalthereto-*is supplied to the deector rings through vthe conductor 40. Theangular distance between the teethi42a and 43 indicates. as will beexplained more fully hereinafter; the distance between the unknown'position and'a Afixed base epoint. The distance between the unknownfposition and a. second'iixed4 base point is indicated'by. the thirdtooth'lid, shownby dotted lines. Y

The signal pulse can also be employed.l for the =`purpose of 'changingthe. intensity of the `4 cathode ray instead of causing its deviation.If, for instance, the intensity of the cathode ray be brought to zero orto the neighborhood of zero, the pulse will result Ain an interruptionof the continuous line of the circle traced by the cathode ray. Anarrangement of this nature is illustrated in Fig. 3. Upon reference tothis iigure it may be noted that the apparatus corresponds, for the mostpart, with that of Fig. 1. Ihe principal d'ii'erence is that the controlgrid 3R is controlled by current impulses indicating the time at whichthe impulse is sent out by the transmitter Afai-1d the time at which theretransmitted impulse is received by the receiver. The impulse `from--the transmitter is applied to grid 34 through conductor 4S, while theimpulse from the receiver is applied through conductor 41. Theseconductors are connected to the grid through a condenser 48. The grid isconnected to the potentiometer 36 through 'a resistor 49, and the grid:potential is so adjusted that `when the pulses corresponding totransmission and reception of the signal pulse are applied 'to the gridthrough condenser 48, the intensity of the cathode "ray is brought tothe neighborhood 'of zero, thereby resulting in an interruption of thetrace, as illustrated in Fig. 4 at 5I and 52, respectively. If desired,the cathode ray tube control could be so arranged that the pulses resultin increasing the intensity of the cathode rayv so as to produceluminous spots.

`It should be understood,-however, that thefinventio'n is not limi-tedYto vthe use of cathode-ray oscillographs giving circular traces.-Itfcan-also be put into 'effect with any trace which makes it possibleto locatethe moment of transmission of 'the starting pulse within aconstant time interval 'serving as a basis -fo`r the 'moment ofappearance of the corresponding `return fpulse.

Furthermore, the invention-is not limited t'o the useof a single cathoderay oscillograph used in-'conjunction with either afsingle 'or-1aplurali-ty of oscillators and phaseshifter's. It is 'possible to utilizean equal number of cathode lray ltubes and oscillators and phase'shi-fters, Vwhereby different oscillographs :are lutili'zed,depending-'ion the frequency selected.I An arrangement Yo'fthi's type@is illustrated in Fig. `5, 'tofwhichreferencel is now'had.

The apparatus illustrated-inFigure 5 vmaybe seen to include four cathoderay oscillographs, indicated by vreference characters-53 to 156,1ii1-clusive. These finay correspond in construction with 'the cathode rayoscillograph- I0 Yof Fig. l1. They are connected Ato individual'oscillatorsand`V phase shit-ters '51 vto BIJ, inclusive, correspondingto those indicated by referencecharacters vI-f31to I6, inclusive, inFig. -1. The cathode hray oscillators and phaseshiftersrare:eachiconnected --by three conductors A'corresponding tolvconductors 39, 40 and 4'I.=of Fig. 1, to a selector switch 6|, wherebythe=con`cluctors individual to leachfoscillator and Vphase; shifter maybe-'conn'ecte'd toithe; transmitter lI-andfreceiverlf2- In the'indicatedposition of the selector switch; A'os'cillograph 353 and oscillatoranduphase shifter `S'Iare operativelyfconnected tothe transmitterandi-receiver, and in the other positions,fselectedlonesof lthe othersso. connected. Further description lof this particularembodiment is notdeemed 'necessary, in view of its similarity tothe apparatus describedhereinabove.

The apparatus-at thef'xed base pointslorl'stations B, RC, 'andDincludes'l-receiversll, 65,and

s, norder that station A may distinguish between the various stations B,C, and D, the stations are provided with suitable means for periodicallyinterrupting or modulating the transmission of the stations a certainnumber of times per minute according to characteristic signals, such ascode. Thus, the tooth corresponding to the retransmitted signal formedon the oscillograph at station A will beat its own identifying signal.

Such means at the various stations are indicated i by block diagramslll, li, and 12, respectively. 1

In a system comprising station A and a single fixed base point station,such, for instance, as station B, both stations may transmit on any Wavelength whatever, that is, both stations wmay transmit either onthesamewave length or at `diilerent wavelengths. However, Whenuaplurality of base points or retransmitting stations, such as B, C, D,are used, it is preferable that all of the stations B, C, D, bepermanently tuned for reception to a common Wavelength M, being thatwhich is transmitted by the transmitter H of the station A, and that thestations B, C, D, be tuned to retransmit on a common Wavelength A2. Thismakes it possible to avoid any operational adjustment on the movingobject on which station A is located, such as an airplane, Whose set ispermanently synchronized with the stations. The teeth and otherreference marks, corresponding respectviely to stations B, C and D willappear simultaneously on the screen, but will' coincide only in theparticular case of a distance AB=AC. The use `of different wavelengthsil and A2 avoids the possibility also of any station C retransmitting,in addition `to the pulses from `A, retransmissions of the same pulsesby the other stations B, D, which would give rise to an iniinite numberof reflected teeth.

In operation, the radio transmitting station A transmits a pulse ofgiven frequency. The frequency is determined by the period of time ittakes the cathode ray of the oscillograph to describe its completetrace, and the pulses are transmitted at the moment when the cathode raypasses over a given point of its trace as the beginning of the phases.The station B receives, and after detection, amplification andmodulation, retransmits the pulses it receives. The retransmitted pulseis received at station A and directed to the control system of thecathode ray oscillograph. The result is interpreted on the screen oftube l at station A by a discontinuity of the trace, that is, in thecaseof apparatus corresponding to that of Figure 1, the discontinuity is inthe form of a tooth; in the case of the apparatus of Figure 3, a darkinterval; and also in the case of the apparatus of Figure 3, thediscontinuity may bein the form of a more brilliant spot.

The interval between the initial point of discontinuity and thatresulting from the reception of the retransmitted signal thus measuresan interval of time. This interval of time includes a period of delayinherent in the operation of stations A and B, which is a xed period 4oftime, and the Variable time required, for the initial transmission andreception of the transmitted pulse. If the distance from A to B is lOkilometers, for example, the interval corresponds to aperiod of travelof 1/15,ooo of a second measured, in the case of the circular trace, by1/15 of the distance around the circle or a lag of 24, assuming that therotation of the radius vector is 1,000 revolutions per second. A

Consequently, by observing the positions of' the teeth or other marksproduced on the screen by retransmission by station B, the distancebetween stations A and B can be deduced. By similarly observing on thescreen the actions of marks characteristic of station C, the position ofwhich is xed like that of B, the position of4 station A relative tostations B and C can be deduced from the two observations byconventional means.

As already pointed out, the different stations B, C, and D can bearranged so that their transmission is interrupted periodically acertain number of times per minute according to characteristic signalssuch ascode. In this way the observerV at station A canV readilyVidentify the tooth or other marks on the screen as produced by aparticular station.

From the foregoing it is evident that the present invention provides anarrangement such that:

(1) The distances from the station A to the fixed points B, C, D can beread immediately and without adjustment.

(2) The operation is not liable to being jammed because no periodicsignal transmitted on the wave length of A Will appear on theobservation screen unless it is exactly synchronized for the Indeed@transmission frequency of the pulses. a lag of one revolution in threehundred and sixty thousand revolutions would become apparent on theviewing screen, assuming the rota` tional velocity of the cathode ray isvone thousand revolutions per second, by reason of arotation of theparasite tooth of one degree --per second.

If several transmitters such as A are to -function simultaneously (as inthe case of aircraft flying in formation) mutual jamming can` be avoidedby providing each of them with a characteristic frequency of signaltransmission (frequency of the pulses).

(3) In contradistinction to certain other devices, the device of theinvention will give indications only so long as the indications havesignificance.

The accuracy of the measurements of the device of the invention is afunction of the factors of precision of measurement of a distance by anelectromagnetic wave and of the stability of the time delay in theretransmission of the'pulseenergy through the stations involved, whichare substantially absolute.

The accuracy of the readings being dependent only on a minimum durationof the pulses vconsistent with the energy to be transmitted, it

aerial, the disappearance or maximum ilattening out of a given toothcorresponding to station B will be obtained, and this will give thebearing of station B. The distance to B from A is de` duced from theangular position on the screen of the corresponding tooth. In this casea single retransmitting station is sufficient to determine the locationof point A.

When point A represents a moving object, an

aircraft, for instance, its directional receiving"i aerial Y can,according -toV the invention, be int fmovable'n the movingv object.v'The'moving object will theny have to beorientatedA as a wholecorrecting course to a simple navigational maneuver, therebyconsiderably facilitating the navigation-of th'e aircraft when the dutyof navigating and pilotingr is assumed' by the pilot alone.

The invention includes another methodL-of de termining` theazimuth' ofreference point B- by a simplepiloting maneuver, without the necessity'of employing; any directional receiving` aerial. The; spacing of theto'oth'which indicates the distance to` point B varies according tothedistance between A and "B, In other words, the tooth' moves inproportionas A comes nearer to B, and faster in proportion as the rotative ortranslative velocity of the cathodey ray is greater. A simplecalculation shows, for instance,- that for a speed of 1,000 rotationsper second of the cathode` ray the tooth, of the circular.` trace,rotates at the ratey of about 2.4 degrees in seconds for a variation ofone kilometerin the distance: AB irracorresponding period of time,whichA corresponds to the'speed of an aircraft traveling at 360kilometers-perhour; If the speed of the cathode trace was10,000-revolutionspersecond, then the toothwould rotate at'the rate of24- degrees under the -same conditions. According to the invention, thedetermination ofthe bearing is effectedby the immobilization of thetooth ori-thel oscillograph screen by a1 momentary variation of the pathof flight of the aircraft. which procuressaid immobilizationforms anangle of 90 with the bearing of point B.

From the foregoing it Will be seen-that itis-'defsirable to have.definite frequencies determiningr therate of travelof the indicatingtraceon the screen. Four frequencies are obtainable with thevembodiments ofV the invention described above. A lesser number can beused ifV desired, and as a` matter. of fact, three; frequencies, such asthe frequencies of Li12/3, 4162/3, and 10,000` revolutions per` secondYare sufficient. The lowestfrequency of 412/3 revolutions per second isintended for long. distance-navigation. TheI tooth, assu-ming' acircular trace, then moves 360 for 360o-kilometers. The second mentionedfrequency, namely, that of '4162/3 `revolutions per second, is intendedfor. more Vaccurate navigation and-the tooth moves-` 360?1 lfor. 360kilometers, The third mentioned frequency, namely, that of 10,000revolutions per second,v is intended to. enable solutionof problemsinvolvingthe highestvpossible sensitivity of diffferential measurements.In the last` case, the cathoderayrotates at. aimiximum speed ccnsis'tentWith technique-or at about 10,000 revolutionsper second for an angulardisplacement of 1 for 412/3 meters.

The present invention enables carryingfout. various navigationalmethods-*other than those described-above.

One method concerns navigation With-.the hel-p of any two stations of anetwork of fixed-stations B, C, and D.

The. distances to` the two iixed poi-nts being knowmthe-positionofstation A can be deduced directly by the intersection of two circleswhere short-distances are concerned. If long-distances are. involved,the method used is that of ordinary celestial navigation, wherein thefixed stations. represent fixed heavenly bodies, and the distancesreadfonthe screen represent the radii ofthe circles-of height. andvwherein resolution-of spherical The course 8.. trlangl'esf isf'merely aquestion of elementaryV graphs; This method whichisapplicable not onlyto" aviation', but also to maritime navigation, is not subjectV eitherto visibility of actual heavenly bodies, or to the lack of precision,which increases in proportionto the distance" involved, of goniometricalbearings.`

Another method` relates to navigation by meansof a4 single fixedstation'B, and eliminates need: forfmanipulat'ion-of a directionalaerial.

It has-already been described herein how to obtain: the bearing ofa.single station B, and' the angle and distance defining. the position ofstation'A.A But, in cases where the pilot is flyingalone, it isVdiiiicult for him to-manipulate a directional aerial. The: oscillographbeing set to operateon the highest frequency of 10,000 revolutions persecond, the tooth of theresultant tracev on the screen willv be subjectto appref ciable'. displacement if the pilot navigates inthe directionof station B. tio-nary (momentarily) in the perpendicular direction. Bymaking simple turns, the pilot willl seek for the course whichrendersthe tooth stationary. The bearing is, obviously, at right anglesto saidk course. (The indetermination is removedby the` direction of thevariation in the distance to stationBJ Y A- third method relates tonavigation along a given course,

Certain' countries, the United States' for instance, prefer navigationalmethodswhich X the pilot on his course, theV sole object of this beingto keep him advisedlas to his position. Now, inV addition'to position,the present device makesV it possibleto define the route or courseitself with moreaccuracy and convenience than by such methods;

For illustration, let XY be the course, and'B an'dfC the positions oftwo fixed, retransmitting stations symmetrically located relative tosaid course. -For greater convenience it is provided that said-stationsshall operate with. complementary identification signals, such astheMorse code letters a and'n.

So longas moving station A travels along route XY,=and therefore atequaldistan'ces from the twoV xedV stations, the teeth corresponding totheV retransmissions of stations B and C will be superimposed on thescreen andthe new tooth thus formedwill no longer pulsate since a and nare. complementary. In this way immediate warning Will be available ofany failure of one of the stations-13 and C-nby the appearance ofpulsations'.

so that there is no risk of relying;- on the presence second beintroduced, the very slightest deviation will be perceptibleA Whereas,according: to

presentA methods, the minimum deviation capable of warning the navigatormay amount toV some kilometersv when midway along a marked out i route.-

Inaddition, it will always be possible to ascertain the mileage coveredalong the route (hence the speed) either by deducingA it from distancesvB or C, or by the read-ing of a'thrd tooth issuing from an axiallylocatedstation.v

It will become stas l A fourth method relates to guiding an airplanetoward a landing eld.

If a landing eld be defined by fixed stations B and C located on eitherside of the landing strip, and if XY represents the line of approachperpendicular to base BC at its middle and if, on the planes nearing thelanding eld the highest frequency of 10,000 revolutions per second isintroduced to render perceptible small variations in distance, course XYcan be followed by navigating with the teeth superimposed. Warning ofpassing tle beginning of the landing strip will be given when the teethpass through a minimum on they trace corresponding to 1/2 BC. Thereading of minimum lacking precision, an axially located station may beemployed also.

The last described method can be used for guiding an airplane in landingon an airfield.

In this case the moving station A is not far 'distant from the fixedstations B and C, so that instead of installing retransmission stationsat ITAB "and C, the reflective effect of the Waves transmitted by A onconductors or metallic masses positioned at B and C may b e utilized.

vControl of the correct `location of A along axis perpendicular to thecenter of segment B, C isr obtained by maintaining coincidence, on the-trace;A of the teeth corresponding to the reflections' by B and C ofthe pulses transmitted by A. Any deviationvof A relative to XY willcause sepa- Pration' of the teeth. The passing of A in front of the lineB, C will appear as a minimum or `minor divergence or separationof thereflected zteeth.

x1 The last described arrangement can be com- L;

bined with the use of an axial reference station, -acting as aretransmitter or merely as a reflector, v:for measuring the distancealong the landing axis.

A fifth method provides for guiding such as an .airplane along aselected course toward a target for such as aerial bombing operations.

. ,Q But, as the course followed is not BA but one perpendicular fromthe center of B, C, the distanceread along BA is not suitable for therapid computation of the speed of approach to the 'tar-get. The use of athird axial station D will facilitate the last.

" If the highest frequency be used when in proximity to the target, astudy of the movement of tooth` D will, permit not only observing withprecision the moment of flying over the target, but also `anticipatingsaid moment with increasing accuracy, `which will makeit possible todetermine the parameters of `virtual bombing aim.

` Errors made in dead-reckoning of the position of moving stationA willnot increase in proportion with the distance from the target, and if thedimension of base BC has been chosen sufficiently large the sightingerror will be negligible.

Here again, the accuracy of the method depends only on the stability ofinertia of the radio stations and on the separating power of the highestfrequency.

n win be understood that the invention per@ .by means of electromagneticwaves, including in Y 10 mits of numerous variants in construction andmethods 0f use Within the scope of the invention.

Having described my invention, what I claim as new and useful and desireto secure by United States Letters Patent is:

1. A system of position-finding and navigating by means ofelectromagnetic waves, including in combination, means including acathode ray tube and its beam for periodically describing the same pathto define a continuous trace and located at a point it is desired toorientate, means for transmitting pulses from said point byelectromagnetic waves, means at a pair of spaced apart points serving asreference bases for receiving and retransmitting said pulses, means atsaid base points for interrupting the-retransmission of the pulses in amanner to define complementary code signals, and means for receiving theretransmitted pulses at said rst point in a manner to modify said beamto produce discontinuities in said trace, whereby said discontinuitiesmerge as long as the body remains on al course equidistant from the two`base points and move apart when the body departs from said course.

2. A method of navigating a moving body along a fixed course, whichincludes rotating an electron beam on said body in a manner to produce acontinuous trace, periodically transmitting immanner to producediscontinuities in said trace 4corresponding in number to the bases andbeating according to the codesignals imposed thereon, whereby merging ofthe discontinuities obtains While the moving body remains on the saidcourse and the .beats of the discontinuities nullify each other and saiddiscontinuities move apart when said bcdy departs fromthe course andbecome identifiable.'

`3. A methodaccording to claim 2 wherein the .impulses transmitted` fromthe moving body are received by another fixed base located on the.course and retransmitted to produce a further `discontinuity of saidtrace which is angularly spaced from one of the other discontinuities insaid. trace `while the moving body is still distant fromthelastmentioned base, whereby the distance of the moving body from said lastmentioned base can be computed from the angular displacement of therelated discontinuities.

4. A method according to iclaim 2 wherein close "approach of the mergeddiscontinuities together .toward said rst discontinuity is achieved byarrival of said body along the xed course at a predetermined destinationon said course.

5. A system kof position-finding and navigating combination, meanscomprising a plurality of 4cathode 'ray tubes' having beams arranged forperiodically describing the same traces at different frequencies andlocated at a point it is desired to orientate, means for transmittingfrom said point a brief signal by means of electromagnetic waves of onefrequency, means include ing a direct connection between' saidtransmitting means and thecathode ray tubes for creating a crstdiscontinuity in their traces when said signal is transmitted, means atanother point serving as a reference basefor receiving and retransmttingsaid signal at a second frequency, means at the first 'mentioned' pointfor receiving said retransmitted signal, and meansincluding a directconnection between said receiving means and any of said cathode raytubes at said first mentioned point controlling said beams in responseto said retransmitted signal for creating a second discontinuity in saidtraces.,

6. In a radio orienting. device for an airplane or other moving body,said device being of the type involving a transmitter-receiver and anoscilloscope on the airplane. said transmitter being energized to emitpulses intermittently, said oscilloscope comprising a cathode ray tube,means energizing the same to produce a continuous cathode ray trace ofcircular form on a target, said cathode ray tube having opposed pairs ofdelector plates energized from the transmitter and receiverrespectively, and atleast two fixed distant stations each ,havingareceiver-transmitter for receivingand retransmitting the pulses emittedfrom the transmitter on the airplane; characterized by the fact that thecathode ray tube is provided with ray deecting means consisting ofconducting rings surrounding the cathode ray tube between the delectingplates and target and in axially spaced 'positions and energized fromthe transmitter and receiver respectively in such manner that a firstvisible discontinuity is produced in the trace when the airplanetransmitter emits a pulse, and second and third vdiscontinuities .areproduced in the trace, angularly spaced from each other and from thefirst trace in accordance with the distances and the direction of theairplane from the xed stations as the pulse retransmitted from the fixedstations reachthe airplane receiver.

7; In a radioorientating device for an airplane or other moving. body,said device beingof the type involving a transmitter-receiver and anoscilloscope on the airplane, said transmitter being energized to emitpulses intermittently, said oscilloscope comprising a cathode ray tube,means energizing the same to produce a continuous cathode ray trace ofcircular form, said cathode ray tube having opposed pairs of deflectorplates energized from the transmitter and 'receiver respectively, and atleast two fixed distant stations each having a receiver-transmitter forreceiving and retransmitting the pulses emitted from the transmitter onthe airplane; characterized by the fact that the cathode ray tube isprovided with ray deecting means energized from the transmitter andreceiver respectively in such manner that a rst visible discontinuity isproduced in the trace when-the airplane transmitter emits a pulse, andsecond and third discontinuities are produced in Vthe trace, angularlyspaced from each other and from the rst trace in accordance with thedistances and the `direction of the airplane from the xed stations `asthe-pulses retransmitted from the fixed stations reach the airplanereceiver, and furthercharacterized by `the fact that the transmitters ofthe Xed stations are'provided with means operating to interrupt theretrans-v` mission Yof Vthe pulses in a different manner at each suchstation so as to produce identifying visible beats inthe correspondingVvisible discontinuities of the cathode ray tube trace.

8. An orientating device `according to claim 7 wherein lthe-'meansoperating to interrupt the retransmission of the pulses Vat at least twoof said ixed stations produce interruptions at one Star 12 tionconcurrent with transmission at another station whereby suchinterruptions are not indicated When the airplane is equidistant fromboth stations and said beats are fully visible and identifiable when theairplane is not equidistant from said stations.

9. A direction and distance nding equipment comprising a radio pulsegenerating and transmitting arrangement, a manually rotatable. wavedirective collector, a pulse receiving arrangement coupled with said.collector for receivingpulses which are refleotedback from obstaclessituated within the iield of said pulse transmitter, an oscillographindicator, means synchronized with the pulses of said transmitter forcontrolling the sweep of said indicator, means for applying saidreceived pulses to said indicator to provide, in cooperation with saidsweep, simultaneous indications of the distances of said obstacles .onAsaid indicator and means for obtaining a supplementary indication ofdirection on said distance indicator itself by .adjustment of said wavecollector to a position of zero reception. v

10. A direction and distance finding equipment comprising a radiopulsegenerating and transmitting arrangement, a. rotatable wavedirectivecollector, a pulse receiving arrangement coupled with said collector forreceiving pulses which are reflected back from obstacles situated Withinthe coupled with said'collector for receiving pulses which are reflectedback from obstacles situated screen means for producing a cathode rayand` sweep producing means for causing said ray to describe a continuoustrace on said screen, means synchronized with the pulses of saidtransmitter for controlling the sweep of said indicator, means forapplying said received pulses to said indicator to producediscontinuities in said trace to provide simultaneous indications of thedistances of said obstacles, and means for obtaining a supplementaryindication ofdirection on said indicator Vitself by adjustment of saidwave collector to a position of zero reception.V

12. A direction and distance nding equipment comprising a radio pulsegenerating and transmitting arrangement, a rotatable wave directivecollector, a pulse receiving arrangement coupled with said collector for`receiving pulses which are reflected back from obstacles situatedlWithin the field of said pulse transmitter, an oscillograph indicatorcomprising a iiuorescent screen, means for producing a cathode ray andsweep producing means for causing said ray to describe a .continuoustrace on said screen, means synchronized with the pulsesv of thetransmitter vfor controlling the sweep of the indicator and means forapplying said received impulses -to said indicator to pro.- ducediscontinuities of said trace to provide simul- 13 taneous indicationsof the distances of said obstacles and to obtain an indication ofdirection by an adjustment of said wave collector to a position of zeroreception as shown on said indicator.

ANTOINE DE SAINT-EXUPRY.

REFERENCES CITED The following references are of record in the file ofthis patent:

1,979,225 Y n Hart oct. 30,1934

Numbexj 14 Name Date Lowell Mar. 23, 1937 Gunn Nov. 1, 1938 Smith Jan.10, 1939 Hunter Dec. 17, 1940 Hefele Dec. 31, 1940 Lyman et al Jan. 7,1941 Budenbom July 8, 1941 Gage Sept. 9, 1941 Budenbom Nov. 17, 1942Seeley Aug. 6, 1946

